Method and System for Unconventional Gas Lift Optimization

1. A method for determining a frequency of a multi-rate well testing operation in a gas-lifted hydrocarbon well, comprising: monitoring a well performance characteristic of the well using single-rate well tests; comparing the monitored well performance characteristic to a current well model performance characteristic; if the monitored well performance characteristic differs from the current well model performance characteristic by less than a predetermined amount, injecting an amount of gas into the well based on the current well model performance characteristic; if the monitored well performance characteristic differs from the current well model performance characteristic by more than the predetermined amount, initiating a multi-rate well test, fitting results of the multi-rate well test to a revised well model performance characteristic, and injecting the amount of gas into the well based on the revised well model performance characteristic.

2. The method of claim 1 , wherein the current well model performance characteristic is a gas lift performance curve (GLPC) model derived from a prior fit to the multi-rate well test, and wherein the revised well model performance characteristic is a revised GLPC fit.

3. The method of claim 2 , wherein comparing the monitored well performance characteristic to the current well model performance characteristic comprises: comparing the monitored well model performance characteristic to the current well model performance characteristic only from a no gas lift value up to a maximum production point.

4. The method of claim 2 , wherein a recent history of GLPC shape of fit is used to modify the predetermined amount and a frequency of initiating the multi-rate well test, based on whether a need for the multi-rate well test is signaled.

5. The method of claim 1 , wherein the well is one of a collection of wells, and further comprising: monitoring the well performance characteristic of each of a plurality of wells in the collection of wells using single-rate well tests; comparing the monitored well performance characteristic of each of the plurality of wells to a respective current well model performance characteristic; if the monitored well performance characteristic of one of the plurality of wells differs from the respective current well model performance characteristic by less than the predetermined amount, injecting the amount of gas into the one of the plurality of wells based on the respective current well model performance characteristic; if the monitored well performance characteristic of the one of the plurality of wells differs from the respective current well model performance characteristic by more than the predetermined amount, initiating the multi-rate well test for the one of the plurality of wells, fitting the results of the multi-rate well test to the revised well model performance characteristic, and injecting the amount of gas into the one of the plurality of wells based on the revised well model performance characteristic, wherein hydrocarbon production of the collection of wells is optimized.

6. The method of claim 1 , wherein the current well model performance characteristic is a current representation of production in the well, and wherein the revised well model performance characteristic is a revised production representation in the well.

7. The method of claim 1 , wherein a control valve is associated with the well, and wherein the amount of gas is injected into the well by controlling the control valve.

8. The method of claim 1 , further comprising: generating the current well model performance characteristic by analyzing historical well performance data.

9. The method of claim 1 , further comprising: selecting a number of stages of the multi-rate well test based at least in part on one of: accuracy of multi-rate well test, and a shape of a current GLPC fit.

10. The method of claim 1 , wherein the monitored well performance characteristic comprises one of fluid flow in a portion of the well, temperature of a well fluid, and a pressure of the well fluid.

11. The method of claim 10 , wherein the well fluid is in the well or in a flowline associated with the well.

12. A computer system, comprising: a memory; and a processor in communication with the memory, the processor programmed to determine a frequency of a multi-rate well testing operation in a gas-lifted hydrocarbon well by monitoring a well performance characteristic of the well using single-rate well tests, comparing the monitored well performance characteristic to a current well model performance characteristic, if the monitored well performance characteristic differs from the current well model performance characteristic by less than a predetermined amount, generating a first instruction to inject an amount of gas into the well based on the current well model performance characteristic; and if the monitored well performance characteristic differs from the current well model performance characteristic by more than the predetermined amount, generating a second instruction to initiate a multi-rate well test, and fitting results of the multi-rate well test to a revised well model performance characteristic.

13. The computer system of claim 12 , wherein the processor is further programmed to generate the first instruction to inject the amount of gas into the well based on the revised well model performance characteristic.

14. The computer system of claim 12 , wherein the current well model performance characteristic is a gas lift performance curve (GLPC) model derived from a prior fit to the multi-rate well test, and wherein the revised well model performance characteristic is a revised GLPC fit.

15. The computer system of claim 14 , wherein comparing the monitored well performance characteristic to the current well model performance characteristic comprises: comparing the monitored well model performance characteristic to the current well model performance characteristic only from a no gas lift value up to a maximum production point.

16. The computer system method of claim 14 , wherein a recent history of GLPC shape of fit is used to modify the predetermined amount and a frequency of initiating the multi-rate well test, based on whether a need for the multi-rate well test is signaled.

17. The computer system of claim 12 , wherein a control valve is associated with the well, and wherein the amount of gas is injected into the well by controlling the control valve.

18. The computer system of claim 12 , wherein the processor is further configured to generate the current well model performance characteristic by analyzing historical well performance data.

19. The computer system of claim 12 , wherein the processor is further configured to select a number of stages of the multi-rate well test based at least in part on accuracy of the multi-rate well test.

20. The computer system of claim 12 , wherein the processor is further configured to select a number of stages of the multi-rate well test based at least in part on a shape of a current GLPC fit.